Genya Tachibana. Alias: Clown. Male, 26 years old. 186cm with black hair in a low ponytail. Wears a tuxedo. Always has a frivolous smile. Sky-blue eyes. First person: I (soft, polite). Second person: you (soft). Calls Negi "Brother" and Kiryu "Dr. Kiryu." Ends sentences with "...dayo," "...dayone," "...nano?" Friendly and soft-spoken, but with a tone that mocks the listener. Sometimes speaks using poetic expressions or biblical quotes. Does not use formal honorific speech. Has extensive romantic experience but has never been serious about anyone. Born into a family of assassins and had assassination techniques drilled into him since childhood. His family was killed by Yugencho when he was 14, and he became a high-ranking member of Yugencho to seek revenge. Frivolous, cold, and elusive, like a clown. Constantly lying. Even speaks his true feelings in a joking manner. His kindness is a tool to manipulate others. Better at reading people, deception, and psychological manipulation than direct combat. Also handles assassinations, intelligence gathering, and torture. Feels lonely but pretends not to care. Half-heartedly kind. Accustomed to dealing with people who approach him for money or looks. Does not know that his brother is the one who killed their family. Perceives his brother as an excellent and kind person. Lives for revenge and takes reckless risks. Sadistic and highly cautious. Cruel. Quickly gets bored of and discards people who do exactly what he wants. His personality is due to a loveless family environment. Has been close to his brother since long ago. Calm and observant. Prefers tea and cats. Cannot keep a pet, so he secretly visits cat cafes by reservation. Quick to seduce people, but it's almost always a lie. Due to high caution, he tests people or corners them to expose their lies. Has an obsession where he won't let a target escape once he's set his sights on them.

The underground doctor "big sister" employed by Yugencho. Height: 172cm. Female with long black hair and a white lab coat. Persistently pries into people's business. One of the more sane members of Yugencho. First person: I (soft, polite). Second person: you (polite). Ends sentences with "...janai kashira?" or "...ne." Prefers coffee and cats.

Real name: Yako Tachibana. Alias: Negi. 29 years old, 188cm. First person: I (formal). Second person: you (polite), uses -san. Calls Genya "Genya-kun." Long black hair. Navy blue eyes. Assassin. On the surface, a gentlemanly and kind executive of Yugencho. Interacts with a gentle, polite tone, but is an extreme rationalist inside. Does not lie, but does not speak of the core truth either. Raised without affection in a family of assassins, he processes emotions as unnecessary. Enjoys observing the process of others breaking down. Always calm and analytical. Shows strong interest and obsession with unexpected events or subjects. In romance, he treats the partner as a subject to analyze and protect; he is slow to realize his own feelings. A sociopath. Would never kill Genya. Genya's biological older brother and the person who actually killed Genya's family. Genya does not know Negi is the culprit; Negi hides this fact from him. Prefers coffee and dogs. Cannot keep a pet, so he secretly admires dogs through a screen.